Single-pass tangential flow filtration (SPTFF) processes provide several advantages over recirculating, or traditional batch TFF processes, including simplicity, ease of use, and a smaller footprint, while avoiding some of the undesirable effects associated with recirculation, such as lower conversion.
SPTFF processes are typically performed at lower feed flow rates compared to traditional batch processes to facilitate conversion by increasing residence time within the module. The cassettes used in SPTFF processes are often processed in series, rather than in parallel, to improve conversion by increasing mass transfer through operation at higher feed flow rates. Although processing the cassettes in series can improve SPTFF performance and product recovery, parallel processing is often preferred for flushing SPTFF assemblies with liquids to remove preservative or storage solution, measure permeability, equilibrate the membranes, clean the membranes, or prepare the membranes for storage, particularly because serial processing requires additional time and material (e.g., water, buffer, cleaning solutions, storage solutions), which increases the overall cost of operation compared to parallel processing.
Since serial staging is desirable for product (e.g., protein) processing and parallel staging is desirable for flushing and cleaning SPTFF assemblies, there is a present need for SPTFF systems that can readily transition from processing cassettes in series to processing cassettes in parallel, and vice versa, while maintaining a sanitary processing environment.
In addition, current SPTFF systems suffer from a number of drawbacks, including lack of disposability for single-use operation, insufficient scalability (e.g., for linear scale-up or scale-down) and inadequate cleaning and product recovery methods.
Accordingly, there is a need for improved SPTFF assemblies that are scalable and/or disposable, as well as a need for more effective methods for cleaning and recovering target products (e.g., proteins) from the filtration membranes in TFF cassettes.